1. Field of the Invention
The present invention relates to the field of flat panel displays, and in particular to an organic light emitting diode (OLED) display device.
2. The Related Arts
Active matrix flat panel display devices have various advantages, such as thin device body, low power consumption, and being free of radiation, and are thus widely used. Among them, an OLED (Organic Light Emitting Diode) is a flat panel displaying technique of extremely prosperous future and it shows excellent displaying performance and particularly possesses various advantages, such as being self-luminous, simple structure, being ultra thin, fast response, wide view angle, low power consumption, and being capable of achieving flexible displaying and is thus regarded as a “dream display”. This, in combination with the factor that the facility expenditure is far less than that of thin-film transistor liquid crystal displays (TFT-LCDs), has attracted the attention of major display manufacturers and becomes the mainstream of the third-generation display devices of the field of displaying technology. It is now the time that mass production of the OLEDs is about to come true and advanced researches cause new techniques increasingly emerging. There will surely be a breakthrough process of the OLED displays.
As shown in FIG. 1, a conventional OLED display device comprises an upper substrate 200, a lower substrate 400, an enclosure resin frame 600 hermetically connecting between the upper substrate 200 and the lower substrate 400.
The lower substrate 400 comprises a first electrode 450 and a second electrode 480 that is located above the first electrode 450 and at a top of the lower substrate 400. The upper substrate 200 provides a sole function of serving as a package lid for isolation of moisture. The first electrodes 450 only functions as a pixel electrode (anode). The second electrode 480 (cathode) is generally thinner. Particularly, for a top-emitting OLED, the second electrode 450 must be made transparent and thus it must be even thinner to provide better light transparency. The thinner the second electrode 450 is, the greater the electrical resistance thereof would be. Thus, for a large-sized OLED display device, it is possible that there exists non-uniform in-plane voltage, affecting the homogeneity of displaying and causing undesired issues, such as non-uniform brightness and mura (which refers to a phenomenon of various tracing on a display due to inhomogeneous brightness).